Upgrading Hobbit Server to 4.2.0 and old bb/hobbit clients

If I upgrade my server to 4.2.0 from 4.1.2p1, will I have to upgrade my current bb clients (bb16e1) and the hobbit clients? Will the bb clients and hobbit clients still work with this version of the server? Sorry, I'm new to Hobbit and have had to take on the responsibility.

Thank you.